K 401 v Others

[consistent]

Hi There,

Some niggling questions for the experts

I was wondering why PWK used the K400 series exponential horn over others such as a tractrix? Also if anyone has taken the K401 out of its enclosure free of its motor board and both listened and measured the differences as against being attached to the mount? Is there any difference noticeable? And finally a question on the little fibre washer. It seems to cover the output mesh/hole of the K55 somewhat. Does that matter should more of the K55 apeture be exposed and less of the washer when you look down at the throat of the K401 or fit the driver.

Many thanks

[ZAKO]

If the washer is partially covering the aperture... You have the wrong washer. Yes it does make a difference without the horn not being attached to the front mount. Tracktrix at that time was not PWK,s priority...But that is a good point,,,Why hasnt Klipsch Co used that design on the Khorn now,,,

[BEC]

Here are some measurements I took a couple of years ago. No doubt some of these may vary a bit because of manufacturing tolerances.

Rubber washer ID is 0.72 inch
K-400 throat is 0.70 inch
K-55V (push term) outlet is 0.85 inch
K-55V (solder term) outlet is 0.80 inch
K-55M outlet is 0.72 inch

PWK said the K-400 horn had to be mounted to work right. I believe that the idea is the wood flange helps to complete the horn and prevent a reflection caused by the horn being slightly undersized.

Bob Crites

[bhendrix]

If the washer is partially covering the aperture... You have the wrong washer. Yes it does make a difference without the horn not being attached to the front mount. Tracktrix at that time was not PWK,s priority...But that is a good point,,,Why hasnt Klipsch Co used that design on the Khorn now,,,

They have used the tractrix on the Khorn. It's called the Klipschorn Jubilee.

[JohnA]

I believe Mr. Paul considered the Klipschorn a completed design and it didn't need changing. He was not very recptive to our crossover redesigns and driver changes. After he settled on the K-55-V and K-77 tweeter, he did not change it until he had to because he couldn't get a driver (changing to the K-55-M in 1981) or when people started blowing tweeters regularly (adding the Type AA Xover in the 60s).

Packaging is another issue. The Tractrix horns I'ver noticed have a larger mouth for the same fc (cut-off frequency). That would have forced the top cabinet to be taller. He must not have wanted that.

I have noticed the difference in hole sizes. My washers match the K400 throat size, but my K-55-Vs have a larger outlet and I've wondered if the cylindrical section of the K400 could not be bored out to match and perhaps reduce distortion at high levels.

[djk]

"I've wondered if the cylindrical section of the K400 could not be bored out to match and perhaps reduce distortion at high levels."

I've cut the whole throat off with a die-grinder and used the JBL 2328 2" throat adaptor, much better.

[consistent]

Interesting stuff, thanks guys.

So the washer that came stock with my K55 X's is too small and potentially causing distortion or interference with the proper functioning of the driver. Mmmm this has got me thinking. So what happens without the washer, any testing done?

Cheers

[Islander]

The washer in question may have dried up and shrunk. New ones are available for very little money. If you attach the driver to the horn without a washer, the seal won't be as good and there's a possibility the two metal surfaces might be hard to separate in the future.

[Marvel]

It is there mostly to allow the driver to be screwed on tight.

[WMcD]

For what it is worth, the predecessor to the K-400 was the K-5. It is somewhat closer to a tractrix than the K-400. PWK was mindful of coverage angles.

Apparently the tractrix horn was not well known in the USA at all. The straight axis ones in England were full range so not quite a midrange.

It is interesting to contemplate that if PWK was stationed in England, rather than Hope, a lot things would be different.

Returning to the subject, the K-400 had extended frequency response in the lows and highs, though not by a whole lot. Apparently PWK was looking for that.

Gil

[consistent]

Thanks again guys, most helpful. The one thing I have noticed between the K401 and the Tractrix (not making any changes to the crossover) is the Tractrix seems cleaner more focused than its rival but the K401 has a deeper delivery of instrument/voice tones.

FYI: I have postioned the K401 'out of its box' with Bob's tweeter on the vertical atop the K401 intersecting about 1 metre in front of my listening position. Then carried out the same for the tractrix. Used no measuring devices except my ears.

Cheers

[CaptnBob]

It was very important to Mr. Klipsch that any Klipschorn with a serial number above 14 be easily upgradable to close to current performance. The tractrix would have required an unacceptable amount of woodworking. That may have been part of his thinking - plus he seems pretty heavily invested in the exponential horn in his technical papers.

[DrWho]

PWK switched over to the tractrix when he realized that it would better achieve his design goals...it just took some time before someone (John Post) was able to provide a fully mathematical explanation. I love how PWK never wavered from his designs until better alternatives could be verified. Knowing why something works is every bit as important as making something that works...

[Deang]

Of course, hearing and listening for the improvement is out of the question!